Light-sensitive silver halide emulsions



United States Patent 01 ice 3,525,622 Patented Aug. 25, 1970 US. Cl. 96-102 5 Claims ABSTRACT OF THE DISCLOSURE Silver halide emulsion layers in photographic material are stabilized against spontaneous fogging during storage and/or development by the inclusion therein of a compound having the following general formula:

This invention relates to light-sensitive silver halide emulsions.

Light-sensitive silver halide emulsions are in general characterized by their sensitivity, gradation and fog.

As is well-known, sensitivity, gradation and fog can be regulated by the way of preparing the silver halide and the use of special chemical ingredients effecting a desired improvement or result. Addenda to the emulsion which are of particular importance for the stability of the lightsensitive characteristics of a silver halide emulsion are the so-called stabilizers.

Stabilizers or antifoggants protect the light-sensitive silver halide emulsions against spontaneous growth of fog during prolonged storage or storage at high temperatures and humidities or during development to maximum contrast and speed.

According to the present invention, photographic silver halide emulsions can be stabilized against the formation of spontaneous fog by incorporating in the emulsions certain silver complexing agents, more particularly heterocyclic hydrazone compounds which can be represented by the following general formula (I):

wherein 4,5,6,7-tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole, S-hydroxybenzothiazole,

6-hydroxybenzothiazole,

5 ,6-dimethylbenzothiazole) those of the naphthothiazole series (e.g. naphtho[2,1-d]thiazole, naphtho-[l,2-d]thiazole, S-methoxynaphtho 1,2-d] thiazole,

S-ethoxynaphtho 1,2-d] thiazole,

8-methoxynaphtho 2, l-d] thiazole,

7-methoxynaphtho [2, l-d] thiazole those of the thionaphtheno [7,6-d]thiazole series (e. g. 7-methoxythionaphtheno [7,6-d] thiazole) those of the thiadiazole series (e.g. 4-phenylthiadiazole, 4-ethylthiothiadiazole, 4-benzylthiothiadiazole, 4-benzylsulphonylthiadiazole), those of the oxazole series (e.g. 4-methyloxazole, S-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, S-phenyloxazole), those of the benzoxazole series (e.g. benzoxazole, S-chlorobenzoxazole, S-methylbenzoxazole, 5-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6- dimethylbenzoxazole, S-methoxybenzoxazole, 6-methoxybenzoxazole, S-hydroxybenzoxazole, 6-hydroxybenzoxazole), those of the naphthoxazole series (e.g. naphtho [2, l-d] oxazole, naphtho 1,2-d] oxazole) those of the selenazole series (e.g. 4-methylselenazo1e, 4-phenylsele'nazole), those of the benzoselenazole series (e.g. benzoselenazole, S-chlorobenzoselenazole, 5-methoxybenzoselenazole, 5-hydroxybenzoselenazole, 4,5,6,7-tetrahydrobenzoselenazole), those of the naphthoselenazole series (e.g. naphtho [2,1-d] selenazole, naphtho[1,2-d]selenazole), those of the Z-quinoline series (e.g. the quinoline, 3-methylquinoline, S-methylquinoline, 7-methylquinoline, S-methylquinoline, 6-chloroquinoline, 8-chloroquinoline, 6-methoxyquinoline, 6-ethoxyquinoline, 6-hydroxyquinoline, 8-hydroxyquinoline, etc.), those of the pyrimidine series, those of the quinoxaline series, those of the quinazoline series, those of the l-phthalazine series, those of the 2-pyridine series (e.g. pyridine, S-methylpyridine, S-nitropyridine), those of the benzimidazole series (e.gL l-ethylbenzimidazole, l-phenylbenzimidazole, 1-ethyl-5,6-dichlorobenzimidazole, 1-hydroxy-ethyl-5,6-dichlorobenzimidazo1e, 1-ethyl-S-chlorobenzimidazole, l-ethyl-5,6-dibromobenzimidazole, 1-ethyl-5-chloro-6-amino-benzirnidazole, 1-ethy1-5-chloro-6-bromobenzimidazole, 1-ethyl-S-phenylbenzimidazole, l-ethyl-S-fluorobenzimidazole, 1-ethyl-5,6-difiuorobenzimidazole, 1-ethyl-5-cyanobenzimidazole, 1-( B-acetoXyethyD- S-cyanobenzimidazole, l-ethyl-S-chloro-6-cyanobenzimidazole, l-ethyl-5-fluoro-6-cyanobenzimidazole, 1-ethyl-S-acetylbenzimidazole, 1-ethyl-5-chloro-6- fiuoro-benzimidazole, 1-ethyl-S-carboxybenzimidazole, 1-ethyl-7-carboxybenzimidazole, l-ethyl-S-carbethoxybenzimidazole, 1-ethyl-7-carbethoxybenzimidazole, 1-ethyl-5-sulphamyl-benzimidazole, or l-ethyl- 5-N-ethylsulphamylbenzirnidazole, and

Z' represents the necessary atoms to close a heterocyclic ring containing as heteroatoms one or more nitrogen atoms e.g. a 2H-pyrrole, imidazole, benzimidazole, l-H-indazole, pyrazole, triazole, pyridine, pyrazine, pyrimidine, s-triazine, isoquinoline, quinoline, phthalazine, quinoxaline, quinazoline, cinnoline, phenanthridine or condensed ring systems containing said nuclei e.g. B-purine, pteridine, fi-carboline and phenanthroline.

Compounds according to Formula I above can be prepared according to one of the methods described in our Belgian patent specification 679,558 filed Apr. 15, 1966.

Of the compounds set forth in the following Table 1, those compounds designated 1 and 2 can be prepared in the manner described by Geldard and Lions, J. Am. Chem. Soc. 84, 2262-3 (1962), while compound number 46 can be prepared in the manner described by Lions and Martin, J. Am. Chem. Soc. 80, 3858-65 (1958). The other hydrazone compounds comprehended by general Formula I above can be prepared by the condensation of a hydrazino derivative which corresponds to the heterocyclic ring structure Z, i.e. that ring structure to the right-hand of Formula I carrying a hydrazino group with an aldehyde derivative corresponding to the heterocyclic ring structure Z, i.e. that ring structure at the left-hand of Formula I carrying an aldehyde group. The general method of carrying out such condensation is as follows. 0.025 mole of hydrazino derivative dissolved or suspended in 25 ccs. of ethanol are mixed with 0.025 mole of aldehyde derivative dissolved in 25 ccs. of ethanol. The reaction mixture is refluxed on a boiling water bath for 30 min. After cooling, the formed precipitate is sucked OE and washed with ethanol and dried. In most cases the obtained product is pure enough so that no further purification is necessary. Only the compound is recrystallized from ethylene glycol monomethyl ether.

In the following Table 1 compounds which are particularly suited for use according to the present invention are listed.

he r In cwnjflg I CH=N-NH;If I

S-CaH;

N S 11 C CH=N-NH COOC2H6 I CH;

HaC N 02 mCUChMHj CH=NNH-W [000mm OJhN-NH- Some of the antifoggants described above possess besides their improved antifogging action in respect to common used antifoggants also spectral sensitizing properties for light-sensitive silver halide. A particular useful spectral sensitization is obtained by applying compounds of the the emulsion and the desired eifect, usually said comchloride-bromide emulsions.

wherein:

Z represents the necessary atoms to close a heterocyclic nucleus of the thiazole series (e.g. thiazole, 4- (p-t01yl)- thiazole, 4,5-diphenylthiazole, 4-m-nitrophenylthiazole, 4-p-bromophenylthiazole, 4 methyl-S-ethoxycarbonylthiazole, benzthiazole, carboxylic acid substituted benzthiazole and sulphonic acid substituted benzthiazole) and those of the thiadiazole series (e.g. 4-phenylthiadiazole, 4-ethylthiothiadiazole, 4 -benzylthiothiadiazole and 4-benzylsulphonylthiadiazole), and

Z ha? the same meaning as Z described in general Formu a I. r

The addenda of the present invention can be added to photographic emulsions using any of the well-known techniques in emulsion preparation. For example, they can be added in dissolved state to the silver halide emulsion, or they can be added to the emulsion in the form of a dispersion similar to techniques used to incorporate colour couplers in the emulsion. The stabilizing agents are preferably added to the photographic emulsion after the final digestion or after-ripening, although they can advantageously be added prior to digestion.

The hydrazone compounds described above can 'be used in combination with other stabilizing agents e.g. of the hydroxy-triazolopyrimidine series (azaindolizines), cadmium salts, mercury compounds and with chemically sensitizing compounds, for instance sulphur compounds and noble metal salts e.g. gold salts.

They can also be used in combination with colour couplers, spectral sensitizers, compounds influencing the development e.g. polyoxyalkylene derivatives more particularly those described in the United Kingdom patent specification 954,205, filed 30.6.1960 by Gevaert Photo-Producten N.V.

Other addenda such as hardening agents, wetting agents, plasticizers, developing agents, and optical sensitizing agents can be incorporated into the emulsion in the usual way.

The amount of hydrazone compounds employed in the silver halide emulsion depends on the particular type of the emulsion and the desired effect, usually said compounds are employed in a ratio of 0.05 millimole to 50 millimole per mole of silver halide. In silver chlorlide and silver chloride-bromide emulsions wherein they show useful spectral sensitizing effects (a sensitizing maximum in the range of 420 nm to 520 nm) they are preferably used in an amount of 0.05 millimole to 10 millimole per mole silver halide.

The stabilizing addenda of the invention can be used in various kinds of photographic emulsion, e.g. spectrally nonsensitized emulsions, spectrally sensitized emulsions, X-ray emulsions, and emulsions sensitive to infrared radiation. Various silver salts may be used as lightsensitive salt, e.g., silver bromide, silver iodide, silver chloride, or mixed silver halides, e.g., silver chlorobromide or silver bromo-iodide. They may be used in silver halide emulsions for application in the silver halide complex diffusion transfer process or other transfer processes based on silver halide photography, in which, e.g., tlie diifusion of a developer, a coupler, or a dye is appied.

The stabilizing and anti-fogging action is determined by an incubation test of the emulsions as indicated in the following Table 2. The fog, gradation and sensitivity values are expressed as a relative increase or decrease in respect of a control emulsion (blank). The tested emulsion is a silver bromide-iodide (4.5 mole percent iodide) emulsion. The incubated emulsions are for 5 min. at 20 C. developed in a developing bath of the following composition:

Water-800 ccs.

p-Monomethylaminophenol sulphate-1.5 g. Anhydrous sodium sulphite-SO g. Hydroquinone-6 g.

Anhydrous sodium carbonate-32 g. Potassium bromide--2 g.

Water to 1000 ccs.

TABLE 2 36 hr. at 57 0. and 6 days at 57 C. and relative humidity relative humidity Cone. of 34% 34% A A sensi- A sensitivity fog tivity (lo (den- (log. It sity) A It) 8 In the following Tables 3 and 4 spectral sensitization results are listed respectively obtained with a silver chloride emulsion (Table 3) and a silver chloride-bromide (5 mol percent bromide) emulsion (Table 4). The speed is to be interpretated as an increase of total sensitivity in respect of a control emulsion (blank).

TAB LE 3 Concen- Number of the tration Sensincompound in mg. zation listed in per kg. maxlmum Table 1 emulsion in run. Speed TABLE 4 Concen- Number of the tration Sensiticompound in mg. zation listed in per kg. max mum Table 1 emulsion in mm Speed We claim:

1. A photographic material comprising a silver halide emulsion layer containing a compound according to the following general formula:

wherein:

R is hydrogen or an alkyl radical,

Z represents the atoms necessary for completing a heterocyclic ring, and

Z represents the atoms necessary for completing a heterocyclic ring, containing as hetero atoms only one or more nitrogen atoms.

2. A photographic material according to claim 1, comprising a silver halide emulsion layer containing silver chloride or silver chloride-bromide, the speed of which has been increased by a compound according to the following general formula:

wherein:

2 represents the atoms necessary for completing a heterocyclic nucleus of the thiazole or thiadiazole series, and

2;, represents the atoms necessary for completing a heterocyclic ring, containing as hetero atoms only one or more nitrogen atoms.

3. A photographic material according to claim 1 comprising a silver halide emulsion layer containing a compound according to the following general formula:

wherein:

R is hydrogen or a methyl group,

Z represents the atoms necessary for completing a pyridine nucleus, a quinoline nucleus, a pyrimidine nucleus, a quinazoline nucleus, a phthalazine nucleus, a quinoxaline nucleus, a benzimidazole nucleus, a thiazole nucleus or a benzithiazole nucleus, and

Z represents the atoms necessary to complete a pyridine nucleus or a quinoline nucleus.

4. A photographic silver halide material according to claim 1, wherein the said emulsion contains said compound in a ratio of 0.05 millimole to 50 millimole per mole of silver halide.

5. A photographic silver chloride or silver chloridebromide material according to claim 2 containing said compound in a ratio of 0.05 millimole to 10 millimole per mole silver halide.

References Cited UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R.

IJNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,525,522 Dat d August 25, 1970 Inve mfl Jozef Frans Willems et al It: is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 12 (Compound 11.) change "HH" etc. to HN Column 5 (Compound 32.) change H CCH= etc. to H CUCH= etc.

Column 6, line 45, delete the entire incorrect line and substitute following general formula II in silver chloride and silver Column 7, Table 2, line 60 (in the heading, column 3) Change: A to density 50g ensity almiu my {I f 1%;.)

neva 1% Amen:

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